/Engine/Plugins/Experimental/Water/Source/Runtime/Public/WaterUtils.h
Creates a transientUMaterialInstanceDynamicout of the material interface in input or returns the existing one if it's compatible (same parent material)
a compatible transient MID if InMaterialInterface is valid, nullptr otherwise
static [UMaterialInstanceDynamic](API\Runtime\Engine\Materials\UMaterialInstanceDynamic) * GetOrCreateTransientMID ( [UMaterialInstanceDynamic](API\Runtime\Engine\Materials\UMaterialInstanceDynamic) * InMID, [FName](API\Runtime\Core\UObject\FName) InMIDName, [UMaterialInterface](API\Runtime\Engine\Materials\UMaterialInterface) * InMaterialInterface, EObjectFlags InAdditionalObjectFlags )